1. Field of the Invention
The present invention pertains to exhaust and ventilation apparatus, and particularly exhaust apparatus as is commonly used for cooking appliances.
2. Prior Art
Exhaust systems for use with commercial cooking appliances--such as grills or ovens--are well known in the prior art. Such exhaust systems ar designed to exhaust air laden with fumes and heat out of a kitchen area for improved safety and comfort.
Exhaust systems typically include (a) an exhaust or vent hood for collecting exhaust air and delivering it to an exhaust outlet system, and (b) a make-up air injection system that injects air (forced or unforced, conditioned or unconditioned) into the kitchen area to replace the exhausted air. An example is disclosed in U.S. Pat. No. 3,890,887 to Kaufman, which includes a ventilator door in the front portion of an exhaust hood so as to direct unconditioned make-up air either under the exhaust hood and toward the cooking surface, or outward and downward in front of the exhaust hood. Another example is disclosed in U.S. Pat. No. 4,475,534 to Moriarty, in which make-up air is injected both under an exhaust hood directly over the cooking surface, and above and in front of the cooking appliance so as to be drawn past a cook, over the cooking surface and out through the exhaust hood.
These exhaust systems, as well as others in the prior art, suffer from the disadvantage that make-up air injected underneath an exhaust hood tends to create turbulence under the exhaust hood over the cooking appliance. This turbulence actually tends to deflect heat arising from the cooking appliance, allowing it to escape into the kitchen area. As a result, substantial amounts of conditioned air must be provided into the kitchen area to balance the heated air that has been deflected from the cooking appliance rather than exhausted through the exhaust hood.